concurrent-java

It covers some basic concurrent programs as well as parallel program examples. Interview level material.

Project Structure

This project contains Java examples organized into three main categories:

Starting Point

• SumTask.java - Basic sum computation with single and multi-threaded approaches

📁 Basic Problems (src/main/java/interview/)

Basic concurrency problems and solutions:

Core Problems:

• UnisexBathroom.java - Unisex bathroom problem solution
• UberSeatingProblem.java - Uber seating arrangement concurrency problem
• DinningPhilosophers.java - Dining philosophers problem solution
• BarberShopProblem.java - Sleeping barber problem implementation
• Superman.java - Superman problem implementation
• MultiThreadedMergeSort.java - Parallel merge sort for interviews
• PrintNumberSeries.java - Threaded number series printing
• FizzBuzz.java - Multi-threaded FizzBuzz implementation
• SynchronousExecutor.java - Custom synchronous executor service
• DefferedCallbackExecutor.java - Deferred callback execution system

Bounded Buffer Implementations (interview/boundedbuffer/):

• BoundedBuffer.java - Basic bounded buffer implementation
• BoundedBufferWithMutex.java - Bounded buffer using mutex locks
• BoundedBufferWithSemaphore.java - Bounded buffer using semaphores

📁 Latch Examples (src/main/java/basic/)

Fundamental concurrency concepts and thread management examples:

• CountDownLatchExample.java - Demonstrates CountDownLatch usage for coordinating multiple threads
• CustomThreadExecutorExample.java - Shows how to create custom thread executors
• CyclicBarrierExample.java - Illustrates CyclicBarrier for thread synchronization
• FixedThreadPoolExecutor.java - Implementation of fixed-size thread pool
• Simple.java - Basic threading concepts
• SumTaskCallable.java - Callable implementation for parallel sum computation
• ThreadLocalExample.java - ThreadLocal variable usage demonstration
• TimerExample.java - Timer and scheduled task examples

📁 Exercise Examples (src/main/java/exercise/)

Practical parallel programming exercises:

• MatrixMultiplySolution.java - Parallel matrix multiplication implementation
• MergeSort.java - Concurrent merge sort algorithm

Key Concepts Covered

• Thread Management: Thread creation, pooling, and lifecycle management
• Synchronization: Locks, semaphores, monitors, and condition variables
• Concurrent Collections: Thread-safe data structures
• Executor Framework: Thread pools and task execution
• Classical Problems: Producer-consumer, dining philosophers, sleeping barber
• Parallel Algorithms: Merge sort, matrix multiplication
• Coordination Primitives: CountDownLatch, CyclicBarrier, ThreadLocal

Usage

Each Java file can be compiled and run independently. Most examples include a main method demonstrating the concept.

# Compile and run a specific example
javac src/main/java/basic/CountDownLatchExample.java
java -cp src/main/java basic.CountDownLatchExample

Prerequisites

• Java 8 or higher
• Basic understanding of multithreading concepts